test/codegen: mention in README that tests only run on Linux without -all_codegen

This took me a while to figure out. The relevant code is in
test/run.go (note the "linux" hard-coded strings):

	var arch, subarch, os string
	switch {
	case archspec[2] != "": // 3 components: "linux/386/sse2"
		os, arch, subarch = archspec[0], archspec[1][1:], archspec[2][1:]
	case archspec[1] != "": // 2 components: "386/sse2"
		os, arch, subarch = "linux", archspec[0], archspec[1][1:]
	default: // 1 component: "386"
		os, arch, subarch = "linux", archspec[0], ""
		if arch == "wasm" {
			os = "js"
		}
	}

Change-Id: I92ba280025d2072e17532a5e43cf1d676789c167
Reviewed-on: https://go-review.googlesource.com/c/go/+/222819
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/test/codegen/README b/test/codegen/README
index d6b8cf5b32f76b78d09fde2056be95aeb182cfc6..b803fe585fa5792794e5f038c78d25393c1abda9 100644 (file)
--- a/test/codegen/README
+++ b/test/codegen/README
@@ -16,8 +16,10 @@ step of the top-level test/run.go suite, called "asmcheck".
 
 The codegen harness is part of the all.bash test suite, but for
 performance reasons only the codegen tests for the host machine's
-GOARCH are enabled by default. To perform comprehensive tests for all
-the supported architectures, one can run the following command
+GOARCH are enabled by default, and only on GOOS=linux.
+
+To perform comprehensive tests for all the supported architectures
+(even on a non-Linux system), one can run the following command
 
   $ ../bin/go run run.go -all_codegen -v codegen